Device for temperature compensation of magnetic storage cores in data processing installations



Nov. 21, 1967 K. KUHLMANN 3,354,443

DEVICE FOR TEMPERATURE COMPENSATION OF MAGNETIC STORAGE CORES IN DATA PROCESSING INSTALLATIONS Filed April l7, 1964 FIG./

FIG. 2

2 I i I I 1 I lNVENTOR KARLHE/NZ KUHLMA lV/V A TTORNE Y5 United States Patent O ,3 6 Claims. (Cl. 340-474) This invention relates to information storage systems having magnetic cores and in particular to an arrangement for compensating for temperature Chari es of the cores.

Information storage devices using magnetic cores are well known in data processing installations and the like, and it is known that the magnetic cores are sensitive to ambient temperature conditions because as the temperature of a magnetic core increases, the coercive field intensity reduces and this reduces the switching current necessary for changing the state of magnetization of the magnetic core.

The intensity of the switching current is therefore a function of the temperature and must be decreased as the temperature of the magnetic core increases and the current intensity must, furthermore, be maintained within relatively narrow limits so that the changing of the state of the core can be accomplished while at the same time, extraneous influences are not introduced into the system.

With the foregoing in mind, it is a primary object of the present invention to provide a relatively simple arrangement for compensating for temperature changes in a magnetic core by controlling the switching current so that the switching always is in proportion to the magnetization intensity required for changing the state of magnetization of the core.

Broadly, compensating arrangements of the nature referred to have been contemplated by employing resistors, the resistance of which is a function of the temperature.

Such resistors are connected in parallel with the coils on the cores and serve to bypass a portion of the excitation current. By selecting resistors with a negative co efiicient of temperature, it follows that as the temperature of the core, and therefore of the resistor increases, a greater amount of the excitation current will bypass through the resistor while a smaller amount is supplied to the exciting coil of the core. A high resistance in series with the aforementioned parallel arrangement will insure that the total excitation-current remains about constant.

The arrangement described above however has the disadvantage of entailing a relatively large power loss which shows up in the shunting resistor and also in the series resistor and, furthermore, in order to prevent excessive temperature rise in the shunting resistor, it must itself be of substantial size. This leads to a relatively bulky arrangement, which is objectionable because it is desired for the shunting resistor to be disposed quite close to the magnetic core to which it pertains.

With the foregoing in mind, it is a still further object of the present invention to provide a circuit arrangement designed to compensate for temperature changes in a magnetic core which can be extremely compact and which is conserving of power at all times.

It is also an object of this invention to provide a compensating system of the nature referred to for data processing installations having magnetic storage cores which can be incorporated in substantially any type of installation of this nature.

These and other objects and advantages of this invention will become more apparent upon reference to the following specification taken in connection with the accompanying drawings, in which:

FIGURE 1 shows diagrammatically a compensating system according to the present invention, and

FIGURE 2 shows a portion of the circuit of FIGURE 1 and illustrates a controllable transistor as an important element in the compensating system.

In general, the problem to be solved by the present invention is treated by including in the circuit by means of which the exciter coils for the cores are energized, a current controlling device which is continuously adjustable. The adjustment of the current controlling device is accomplished by establishing two voltages, one thereof being proportional to the exciting current and flowing in the system, and the other thereof being generally proportional to the temperature conditions. The first named voltage is established across a resistor which carries the exciter current and the second mentioned voltage is established across a resistor, the resistance of which is a function of the temperature and which last-named resistor is supplied with current from a separate power source so that it does not carry the exciter current. This last-named resistor is also a relatively high resistor so that it draws only a small current only from its source, whereby the resistor does not become unduly heated by the current flow therethrough.

The differences in the two voltages referred to is utilized as the controlling voltage for the current controlling device.

The arrangement is compact and conserving of power and is simple to incorporate in a data processing system.

Referring to the drawings somewhat more in detail, FIGURE 1 shows an arrangement of columns and rows of magnetic cores 1 making up a storage matrix. Exciter leads lead to the respective columns and rows of the matrix for supplying current to the coils (not shown) and pertaining to the several cores 1.

A source of voltage 3 is connected in circuit with the leads 2 by way of switches 4 so that the switches, under the control of a read-out device or the like (not shown) can control the columns and rows of the matrix.

The amount of exciter current which flows in the system upon closing of a switch 4 is determined by a current control valve or device 5 which is located in the circuit leading to power source 3.

The exciter current is made up of two branches I1 and I2, the latter branch flowing through resistor 7 and being uncontrolled, whereas branch 11 flows through device 5 and is the controlled portion of the current.

Device 5 has voltage sensitive control means pertaining thereto to which are connected the lines 8. One line 8 leads to one end of a resistor 9 through which the exciter current portion I1 flows so that the voltage drop across resistor 9 is proportional to the said portion of the exciter current.

A second resistor 10, which may be variable in nature, and the resistance of which is a function of the tempera ture, is connected at one end to the other of the lines 8. This second resistor is supplied by current source 11 through a relatively high resistance 12 so that only a small current flows through resistor 10, which current is maintained more or less constant because of the size of the resistance 12. The small current through resistor 10 does not appreciably increase the temperature thereof so that the temperature of resistor 10 is substantially a measure of the ambient temperature condition. The resistor 10 can be made relatively small and can therefore be placed quite close to the storage core so that its temperature is very nearly proportional to the temperature conditions of the cores.

It will be noted that the respective currents in resistors 9 and 10 are in the same direction and that the ends of resistors opposite their connections to lines 8 are interconnected so that between the lines 8 there will exist a voltage difference which effects the control of the device 5. The device therefore responds to a first voltage drop across resistor 9 which is a function of portion 11 of the exciter current, and a second voltage across resistor which is substantially a function of the temperature conditions under which the cores 1 are operating.

FIGURE 2 shows a specific circuit arrangement for practicing the principles of the present invention. In FIG- URE 2, transistor 13 is provided as the current controlling element, and in the emitter-base circuit are arranged the temperature sensitive resistor 14 corresponding to resistor 10 of FIGURE 1, and the resistor 15 corresponding to resistor 9 of FIGURE 1. These resistors are serially arranged so that the voltage drops thereacross are in respectively opposite directions and therefore the actual voltage in the emitter-base circuit is the difference between the voltages across the said resistors. Inasmuch as the temperature coefficient of resistor 14 is negative, it follows that the greater the temperature of resistance the smaller its voltage and, assuming that the voltage across resistor 14 is higher than that across resistor 15, the voltage difierence across the two serially connected resistors will drop as the temperature of resistor 14 increases.

It is conceivable, of course, for the voltage across resistor 15 initially to be greater than that across resistor 14, and in that case, the resistor 14 would have a positive temperature coefficient so that, with increasing temperature, the voltage across the serially connected resistances would grow smaller. It will be evident that the selection of resistor 14 would be determined by the particular type of control element employed at 13 and the manner in which it was connected in circuit.

In any case, it will be apparent that only small amounts of power are required to effect the control and that the excitation current flowing in the matrix can be so regulated by the system according to the present invention that the cores can have the state of magnetization thereof altered without disturbances because of excessive switching currents in the matrix. Preferably the transistor employed would have an emitter-base circuit of relatively high ohmic resistance which would maintain the power loss small and also permit close control of the exciter current.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What is claimed is:

1. A temperature compensating device for controlling the switching current in magnetic switching cores comprising; first resistor means through which a portion of said switching current flows to create a first voltage drop thereacross, a continuously controllable current valve means in series with said first resistor and having voltage sensitive control means, temperature sensitive resistor means responsive to changing temperature conditions at said switching cores, a source of relatively constant current flowing through said temperature sensitive resistor means to provide a second voltage drop thereacross which is a function of temperature at said switching cores, said constant current being independent of the current through said switching cores, and circuit means interconnecting said temperature sensitive resistor means with said first resistor means and said current valve means so that the difference between said first and second voltage drops is utilized in controlling said current valve means.

2. The device as claimed in claim 1 in which the controllable current valve meanscomprises a transistor having an emitter-base circuit in series with said first resistor means and said temperature sensitive resistor means so that the difference in said first and second voltage drops is the actual voltage in said emitter-base circuit and in.

which said temperature sensitive resistor means has a negative temperature coefficient.

3. The device as claimed in claim 2 in which said temperature sensitive resistor means has a positive temperature coefiicient.

4. A temperature compensating device for controlling the switching current in magnetic switching cores comprising; first resistor means through which a portion of said switching current fiows to create a first voltage drop thereacross, a continuously controllable current valve means in series with said first resistor and having volt-age sensitive control means, temperature sensitive resistor means responsive to changing temperature conditions at said switching cores, a source of relatively constant current flowing through said temperature sensitive resistor means to provide a second voltage drop thereacross which is a function of temperature at said switching cores, said constant current being independent of the current through said switching cores, said controllable current valve means having a load circuit which is in parallel with said switching current, and a control circuit which is in parallel with said temperature sensitive resistor means.

5. The device as claimed in claim 4 in which said controllable valve means is a transistor and in which said temperature sensitive resistor means has a negative temperature coefficient.

6. A temperature compensating device for controlling the switching current in magnetic switching cores comprising; a first circuit branch having a resistor in series therewith through which the uncontrolled portion of the switching current flows, a second circuit branch in parallel with said first circuit branch and through which the controlled portion of said switching current flows, said last named banch comprising first resistor means through which a portion of said switching current flows to create a first voltage drop thereacross, a continuously controllable current valve means in series with said first resistor and having voltage sensitive resistor means responsive to changing temperature conditions at said switching cores, a source of relatively constant current flowing through said temperature sensitive resistor means to provide a second voltage drop thereacross which is a function of temperature at said switching cores, said constant current being independent of the current through said switching cores, and circuit means interconnecting said temperature sensitive resistor means with said first resistor means and said current valve means so that the difference between said first and second voltage drops is utilized in controlling said current valve means.

References Cited UNITED STATES PATENTS 3,106,645 10/1963 Kaufman 30788.5

BERNARD KONICK, Primary Examiner.

R. MORGANSTERN, Assistant Examiner. 

1. A TEMPERATURE COMPENSATING DEVICE FOR CONTROLLING THE SWITCHING CURRENT IN MAGNETIC SWITCHING CORES COMPRISING; FIRST RESISTOR MEANS THROUGH WHICH A PORTION OF SAID SWITCHING CURRENT FLOWS TO CREATE A FIRST VOLTAGE DROP THEREACROSS, A CONTINUOUSLY CONTROLLABLE CURRENT VALVE MEANS IN SERIES WITH SAID FIRST RESISTOR AND HAVING VOLTAGE SENSITIVE CONTROL MEANS, TEMPERATURE SENSITIVE RESISTOR MEANS RESPONSIVE TO CHANGING TEMPERATURE CONDITIONS AT SAID SWITCHING CORES, A SOURCE OF RELATIVELY CONSTANT CURRENT FLOWING THROUGH SAID TEMPERATURE SENSITIVE RESISTOR MEANS TO PROVIDE A SECOND VOLTAGE DROP THEREACROSS WHICH IS A FUNCTION OF TEMPERATURE AT SAID SWITCHING CORES, SAID CONSTANT CURRENT BEING INDEPENDENT OF THE CURRENT THROUGH SAID SWITCHING CORES, AND CIRCUIT MEANS INTERCONNECTING SAID TEMPERATURE SENSITIVE RESISTOR MEANS WITH SAID FIRST RESISTOR MEANS AND SAID CURRENT VALVE MEANS SO THAT THE DIFFERENCE BETWEEN SAID FIRST AND SECOND VOLTAGE DROPS IS UTILIZED IN CONTROLLING SAID CURRENT VALVE MEANS. 